The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 199 30 592.7, filed on Jul. 2, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention concerns a headbox with a turbulence generator and a jet comprising an upper lip and a lower lip, whose interior space formed between the upper and the lower lip is subdivided by several lamellae.
2. Discussion of Background Information
Such a headbox is used for the production of a suspension stream, that is as wide as the machine, in a machine for the production of a material web. The material web formed from the suspension can especially be a paper or cardboard web.
In the headbox of this type known hitherto, the lamellae are generally designed to be rigid and jointed or flexible, and are fixed to special fittings which are provided between the rows of turbulence pipes. Headboxes with flexible lamellae are described, for example, in the publications DE 42 25 297 C2, DE-OS 22 40 596, and U.S. Pat. No. 4,566,945. These lamellae can freely adjust to the forces of the material stream flowing through. However, in headboxes known, for example, from the publications DE 43 07 143 C2 and U.S. Pat. No. 4,941,950 relatively rigid lamellae are provided which are connected to the turbulence generator by a joint. Flexible lamellae without joints float in the suspension so that their position in the jet space is determined by the prevailing hydraulic pressure relationship. The disadvantage here is that the lamellae are not free of bending stresses, in the position assumed during operation, because in headboxes with parallel positioning of the rows of turbulence pipes the mounting direction is not identical to the lamellae direction. The resultant restoring forces adversely affect the hydraulic relationship. Additionally, the durability of the lamellae is reduced by the bending stresses at the mounting point. Jointed lamellae entail a great overall height which is especially disadvantageous if a larger number of rows of pipes is necessary, e.g.,xe2x89xa74. Greater overall heights are expensive and, for reasons of space, frequently also are not feasible without technological disadvantages.
It is the object of the invention to create an improved headbox of the type cited earlier in which the above mentioned disadvantages are eliminated. Achieved hereby, especially, shall be an inexpensive lamellae and turbulence generator arrangement with jointless lamellae.
This object is attained by the invention in that the turbulence generator comprises several at least essentially, parallel rows of pipes, in that the lamellae are mounted between the rows of pipes and converge in the direction of the jet outlet slit, while at least some of these lamellae within the jet area have course that deviate from the longitudinal axis of the turbulence generator, and in that the end sections of the lamellae that are mounted between the rows of pipes and parallel thereto each transition through a bend into a lamella section located inside the jet space, that is angled to the longitudinal axis of the turbulence generator.
Inexpensive production is possible, since the rows of pipes of the turbulence generator are, at least essentially parallel to one another. Also, this results in a low overall height in comparison to a swept back arrangement. The lamellae mounted between the rows of pipes insofar as they have a course within the joint area differing from the longitudinal axis of the turbulence generator, have a bend in the vicinity of the mounting point, by which the desired angle of each lamella section inside the jet area can be determined in advance. This makes it possible in particular for the angles of the lamella sections inside the jet space and predetermined by the particular bend to at least essentially correspond to the angles required for operation. Consequently, larger bending stresses no longer occur during operation.
Especially advantageous, as well, is that the lamellae can now be constructed without a joint.
In a preferred practical embodiment of the headbox according to the invention, the lamella sections located in the jet area have a course that is at least eventually straight.
The lamellae end preferably inside the jet.
In order to keep the overall height as low as possible, the thickness of the lamellae is preferably smaller than about 18 mm, especially in the area of the mounting point.
In a useful practical embodiment the bend angles of neighboring lamellae are different and are sized such that imaginary extensions of the lamellae and the jet lips intersect in one line.
According to the invention the bend angles have values between about 0xc2x0 and 20xc2x0, preferably between about 0xc2x0 and 12xc2x0.
It is also advantageous when, viewed in the z-direction of the headbox, the bend angles of those lamellae attached a distance away from the axis have greater values than the lamellae attached closer to the axis.
When the lamellae in the jet area are attached symmetrically, it is advantageous if the bend angles of two symmetrically positioned lamellae have the same value.
Further, it is advantageous when the lamellae are made of carbon fiber laminate, glass fiber reinforced plastic and/or polycarbonate, e.g., such as Makrolon(copyright), Lexan(copyright) and/or similar.
It is advantageous to provide at least one lamella, that is one-pieced, bent, and cut from the solid.
According to a preferred practical embodiment of the headbox according to the invention, however, at least one two-pieced lamella can also be provided, whose two parts are glued together. Here, the glue joint is most usefully positioned in the vicinity of the lamella section mounted between the rows of pipes.
In one preferred embodiment the glue joint is located completely outside of andxe2x80x94in the direction of flowxe2x80x94in front of the jet area adjacent to the turbulence generator. Thus the glued surfaces are not exposed to any aggressive paper suspension and protected accordingly. With the glue joint located outside of the jet area, the glued surfaces are also outside of the lamella area in which limited bending stress can still occur, thereby achieving greater durability.
The two parts of the lamella can be glued together by flat glue surfaces, or by glued surfaces that are shaped in complementary fashion so as to interlock.
In one advantageous embodiment of the headbox according to the invention the two parts of the lamella are glued together by glued surfaces that run generally diagonally to the longitudinal extent of the relevant lamella section, when viewed in cross-section. If the glue joint is provided, again, in the area of the lamella section between the rows of pipes, the angle of the diagonal glued surfaces can be selected in reference to the angle of the section of the relevant lamella located in the jet space.
In one preferred practical embodiment the diagonal glued surfaces of each lamella are at least approximately parallel to the orientation of the lamella section located inside the jet area. An overall beneficial bending and bonding stress is achieved with such diagonal glued surfaces.
The two lamella parts glued together can additionally be bolted.
In one preferred practical embodiment the lamellae are manufactured with formed bends.
It is also advantageous when the lamellae are attached to the turbulence generator, or respectively its pipes, in an interlocking manner. In this case it can be useful when the lamella sections mounted between the rows of pipes are provided with transverse grooves, which advantageously engage ribs or projections provided on the pipes of the turbulence generator.
It is advantageous when at least some of the lamellae can be removed from the side.
In general, it is also possible for at least some of the lamellae or lamella sections located in the jet space to be mounted with a bayonet fastener and to be removable in the direction of the machine.
Two-piece lamellae with a bayonet fastener are already known from DE 196 52 983 A1.
The present invention is directed to a headbox that includes a turbulence generator including a plurality of essentially parallel rows of pipes and a jet including of an upper lip and a lower lip arranged to form a jet space and a jet outlet slit. A plurality of lamellae are arranged to subdivide the jet space, and the plurality of lamellae include end sections and lamella sections. The end sections are mounted between the plurality of essentially parallel rows of pipes, and at least some of the lamella sections are arranged to converge over a bend point in a direction of the jet outlet slit and, thereby, are angled toward a longitudinal axis of the turbulence generator.
According to a feature of the invention, the angle of the lamella sections located inside the jet space may correspond at least essentially to an angle required for operation.
In accordance with another feature of the invention, the plurality of lamellae may each be formed without a joint.
According to still another feature of the present invention, the lamella sections located in the jet space can have an essentially straight course when viewed in cross-section.
In accordance with a further feature of the instant invention, the plurality of lamellae can have ends which are located within the jet space.
A thickness of the plurality of lamellae can be smaller than about 18 mm, and, in particular, the thickness of the plurality of lamellae in a mounting area can be smaller than about 18 mm.
Further, bend angles of neighboring lamellae may be different and the lamellae may be sized such that imaginary extensions of each lamella, the upper lip, and the lower lip are arranged to intersect at a common line. The bend angles may be between about 0xc2x0 and 20xc2x0, and, preferably, the bend angles are between approximately 0xc2x0 and 12xc2x0. When viewed in a z-direction of the headbox, the bend angles of the lamellae mounted a distance away from the longitudinal axis may have higher values than the lamellae mounted closer to longitudinal axis.
In accordance with another feature of the invention, the lamellae in the jet space can be symmetrically mounted and bend angles of two lamellae symmetrically mounted to one another can have a same value.
The lamellae may include at least one of carbon fiber laminate, glass fiber reinforce plastic, and polycarbonate. Further, the polycarbonate can include at least one of Makrolon(copyright) and Lexan(copyright).
According to another feature of the invention, at least one lamella may include a single piece element with a bent portion.
In accordance with still another feature of the present invention, at least one lamella may include a two-pieced lamella having two pieces which are glued together. Further, a glued joint can be located in the end section and can be mounted between the plurality of rows of pipes. A glue joint can be located completely outside of the jet space. Still further, a glue joint may be located upstream of the jet space, relative to a flow direction, and adjacent to the turbulence generator. The two pieces of the two-pieced lamella can include flat glue surfaces which are glued together. Further still, the two pieces of the two-pieced lamella can include complementary shapes adapted to interlock. The two pieces of the two-pieced lamella may include surfaces that are generally diagonal to a longitudinal extent of the relevant lamella section. A glue joint can be located in the area of the end section, and an angle of the diagonal glue surfaces can be a function of an angle of the lamella section in the jet space. The diagonal glued surfaces may be at least almost parallel to an orientation of the lamella sections.
Moreover, the two pieces of the two-pieced lamella can be additionally bolted together.
According to a further feature of the invention, the plurality of lamellae may be formed with integral bend points.
In accordance with a still farther feature of the instant invention, the plurality of lamellae can be interlockingly connected with the turbulence generator.
The plurality of lamellae may be interlockingly connected with the plurality of rows of pipes. Further, the end sections can include transverse grooves, and the plurality of pipes can include one of ribs and projections. The grooves may be adapted to engage the one of ribs and projections.
According to still another feature of the invention, at least some of the plurality of lamellae can be removed laterally from a side of the turbulence generator.
Further, bayonet fasteners can be included. At least some of the plurality of lamellae may be mounted by the bayonet fasteners so as to be removable in a flow direction.
The present invention is directed to a headbox that includes a turbulence generator, a jet comprising an upper lip and a lower lip arranged to form a jet space and a jet outlet slit, and a plurality of lamellae. Each lamella includes a lamella end coupled to the turbulence generator, a lamella section located within the jet space, and a bend region. The bend region is located between the end section and the lamella section.
In accordance with a feature of the invention, the turbulence generator may include a plurality of substantially parallel rows of pipes, and the lamellae may be located between adjacent rows. The lamella sections may be arranged to converge in a direction of the jet outlet slit.
According to another feature of the present invention, the lamellae may be arranged to subdivide the jet space. The lamellae may be arranged to substantially equally subdivide the jet space.
In accordance with still another feature of the instant invention, the lamellae may be arranged substantially symmetrically to the jet outlet slit. A longitudinal extent of each lamellae may converge to a common line. The common line may be located downstream, relative to a flow direction, of the jet outlet slit.
The end sections may include first and second parts coupled together. The first and second parts can be coupled together with glue. Further, the first and second parts can be coupled together with bolts,
In accordance with yet another feature of the present invention, the end sections can include transverse grooves, and the plurality of pipes include one of ribs and projections. The grooves may be adapted to engage the one of ribs and projections.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.